Electrolyte for electrolytic cells, such as lightning-arresters, condensers, and the like.



ELEGTROLYTE FOR nnnoinorzrre CELLS, SUCH AS DENSERS, AND THE LIKE.

1 370,784. No Drawing, To all whom it may concern."

Be it knownthat and a resident gheny and State of Pennsylvania, haveinvented a new and useful Improvement in an Electrolyte for ElectrolyticCells, Such as Lightning-Arresters, Condensers, and the like, of whichthe following is a specification.

My invention relates to electrolytes which may be used in electrolyticcells such as lightning arresters, condensers, rectifiers and the like.

More particularly, to ,certain electrolytes which form high-re sistancefilms upon the surfaces of aluminum, tantalum, platinum, magnesium, andother film-forming metals when they'are immersed in these electrolytesand subjected to electric current.

It is well known that films,'-which are formed upon aluminum and otherfilmforming' metals by immersing them in a suitable electrolyte andsubjecting them to an electric'current flow, possess the property ofallowing current to flow from. the electrolyte to the electrode with butof opposing strongly the current tendmg to flow from the electrode tothe electrolyte. To current flowing in the last indi-' cated direction,sively thin, presents ance and a high dielectric strength and,consequently, is able to withstand considerable voltage withoutrupture.-

Heretofore, it has 'been'subst'antially impossible toform permanenthigh-resistance films on the film-forming metals of the .usualcharacter, which films constantly resist substantially high voltagepressures. As a result, it has been necessary to provide electrolyticcells of large capacityv and adapted" for big -voltageservicewith anunduly large number of plates or electrodes which have addedconsiderably to the weight and the first cost of such cells One objectof my invention is to provide electrol es of the character indicated, wereby high may be conveniently and chea ly formed on film-forminmetals,-which high ' Specification of Letters mm. ApplicationfiledOctober 2, 1914. Serial No. 864,666.

'I, LEWIS W. GHUBB, a

citizen of the United States,

of Edgewood Park, in the county of Alle-- my invention refers littleopposition,

the film, althoughexces a high specific resistmonium borate,

tive abovereslstance films.

will be'of er res stante and h g r d e tr LIGHTNING-ARRESTERS, CON-PatentedJuly 2, 1918.

strength 7 than those of 'films heretofore formed with the commonelectrolytes.

Other features of novelty of my invention will be more fully disclosedin the following description to which reference may now be had.

Electrolytes of various characters have been used which generallycomprised chemical constituents that imparted either basic or neutralreactions to the electrolytes. I am also aware that electrolytes havebeen acidulated bythe addition of small quantities of a suitable ample,an electrolyte consisting ofa solution of borax which has been slightlyacidulated with a small quantity of boric acid. However, I havediscovered that, unless the electrolyte contains a large amountproportion to the amount lution, it is not capable high-resistance filmof maximum strength "upon the film-forming metal electrodes.

By means of a long series of tests, I have discovered that, if certainsalts which, in solution, are capable of forming films on film-formingmetals, are combined with suitable acids in the proper roportion, theresistance of the films may he considerably increased. To obtain themost efi'ective results, the acid constituent of the electrolyte Lshouldcomprise a relatively large portion of the dissolved chemicals. Forexample, I have made a most desirable prising a solution of ammoniumborate, (NH BO and boric acid (H BO which solution has. very differentfilm forming characteristics for difierent relative percentages of thesalt and the acid constituents. of boric acid is added of salt in thesothe ammonium borate being largely in excess, the. films formed'on thefilm-forming metal electrodes,- as, for

instance, aluminum electrodes, are capable of resisting voltages ofabout 300 volts only wlthout rupturing. By increasing the proportion ofthe boric-acid constituent relato the. ammonium .borate constituent, Ihave found that, within certain limits, the dielectric resistance of thefilms formed on the electrodes may-be rapidly increased.

Films ot highest resistance .over range of impressed voltageslnay be -awide formed acid or acids, as, for 8X' of acid in of developing a.-'

When a relatively small percentageto a solution of am and ammoniumtartrate;

when the boric acid constituent comprises between .75 per cent. to 98per cent. of the total gram-molecules of the soluble material present,namely, borate, although filmshav'ing high specific resistance may beformed when the boricfacid constituent comprises at least per cent, ofthe total gram-molecules of the soluble material present. When theboric-acid constituent comprises substantially 97 per cent. and not over98 per cent. of the total gram-molecules of the soluble material, thefilms are capable of resisting substantially 500 volts without beingruptured.

While a solution of bor c acid and ammonium borate is particularlydesirable because of its ability to form very high-resistance fi s,solutions of other acids and other salts of acids may be suitable todevelop high-resistance films on electrodes, and I wish it to beunderstood that my invention -may be applied to electrolytes comprisingsolutionsof substances which form insoluble compounds of thefilm-forming metals. For example, I have made electrolytes having goodfilm-forming qualities of citric acidand ammonium citrate and oftartaric acid Other acids and other salts of acids which may be usefulin making electrolytes in accordance with my.

inventlon and which may be characterized as being suitableto formhigh-resistance films are mentioned above, are immersed 1n solutionsthat contain ingredients capable of formin films thereupon byelectrolytic ac t1on, w ich films may serve asdi-electrics of hlgher orlower resistance, such solutions may be characterized as film-formingelectrolytes. All such the term fil1n-forming as it is used n the subsoined claims.

An electrolyte comprising boric acid and ammonium borate is particularlydesirable because the solution 'formed is an inorganic solution whichdoes 'not rapidly deteriorate.

This is highly desirable because alummum cells are commonly used aslightning arresters which are usually disposed in inaccesslble placeswhere the cells may not be frequently inspected. In the past, manyelectrolytes have been made of organic substances in which fungusgrowths develop,

boric acid and ammonium properties for a long time.

carbonates, Of course, it

substances as hereinbe-[ fore indicated are embraced by terial.

thereby rendering the aluminum cell inefiective' as a lightmn arrester.In an electrolyte of boric aci and ammonium borate, fungus growthscannot ,develop. Again, such an electrolyte maintains its chemical Inpractice, it will'probably be advantageous to add an excess of crystalsofboric acid to the electrolyte. In other words, the electrolyte shouldconsist of at least a saturated solution of the acid, in this case,boric acid, which is accomplished by adding the above-mentioned excesscrystals.

Of course, any solvents may be used in which the salts and the acidsselected for my and frequently'it may electrolyte are soluble, bedesirable to use aqueous solutions for electrolytes embodying myinvention, but

it will beapparent that I do not desire to lifii't my invention toaqueous solutions 0 A? electrolyte made in accordance with my inventionand containing a solution of boric. acid and ammonium borate may formfilms on 'film forming metals which are capable of resisting a pressureof substantiallv 500 volts without bein ruptured. In vie-.1 of this, thetotal num er of plates or electrodes comprising a cell, which is adaptedto be utilized at a certain voltage, may be materially reduced, orcells-may be made which are adapted for use under very highvoltageservice conditions, which cells will not embody a large number of platesor electrodes.

While I have described in detail one electrolyte made in accordance withm invention, it will be understood that I esire to have only suchlimitations imposed as are ndicated in the appended claims.

I claim as my invent'ron:

1. A film-forming electrolyte containing a solution of an acid and asolution of a salt,the number of gram-molecules of acid present being45% to 98% of the total gram-molecules of the soluble material.

2. A film-forming electrolyte containing a solution of an'acid and'asolution of an ammonium salt,-the number of gram-molecules of acidpresent being-45% to 98% of the total gram-molecules of the soluble ma3. A' film-forming electrolyte containing a solut1on ,'of an acid and asolution of ammonium borate, the number of gram-molecules of acldpresent being 45% to 98% of the total gram-molecules of the solublematerial.

4. A film-forming electrolyte containing a solution of boric acid and asolution of a salt, the number of gram-molecules of boric acid presentbeing 45% to 98% of the total gram-molecules of the soluble material.

5. A film-forming electrolyte containing a solution of boric acidconcentrated to at least saturation and a smaller amount, relative tothe amount of dissolved acid, of a solution of an ammonium salt..

6. A film-formingelectrolyte containing a solution of boric acid and asolution of an ammonium salt, the number of gram-molecules of boric acidpresent being 45% to 98% of the -total gram-molecules of the solublematerial.

7; An electrolyte containing a solution of boric acid and a solution ofammonium borate, the number of gram-molecules of boric acidpresent beingto 98% of the total gram-molecules of the soluble material.

8. A. film-formingelectrolyte containing a solution of boric acid and asolution of a salt, the number of gram-molecules of boric acid presentbeing 80% to 98% of the total gram-molecules of the soluble material.

molecules of boric acid 9. A film-forming electrolyte containing asolution of boric acid and a solution of an ammonium salt, the number ofgrampresent being 80% to 98% of the total gram-molecules of the solublematerial.

10. An electrolyte containing a solution of boric acid and a solution ofammonium borate, the number -of gram-molecules of.

boric acid present being 80% to 98 of the total gram-molecules of thesoluble ma terial 11. A film-forming electrolyte containing a solutionof boric acid and a solution of a salt, the number of gram-molecules of'a solution of boric of the total boric acid present being substantially97% ofthe total gram-molecules of the soluble material.

12. A film-forming electrolyte containing acid and a solution of anammonium salt, the number of grammolecules of boric acid present beingsub stantially' 97% of the total gram-molecules of the soluble material.a

13. An electrolyte containing a solution of boric acid and a solution ofammonium borate, the number of gram-molecules of boric acid presentbeing substantially 97% gram-molecules of the soluble material. 7

14'. A film-forming electrolyte containing a solution of an acid and asolution of a salt of the same acid, the number of grains molecules ofthe acid present being to 98% of the total gram-molecules of the solublematerial.

15. A film-forming'electrolyte containing a solution of an acid and asolution of an ammonium salt of the same acid, the number ofgram-molecules of acid present being 45% to 98% of the totalgram-molecules of the soluble material.

In testimony whereof I have hereunto subscribed my name this 29th day ofSept,

LEWIS W. CHUBB. Witnesses B. B. Hines, M. C. Mnnz

